Question

What is the standard deviation of the set of data?

21, 6, 18, 21, 20, 14, 19

Answer 1

I just don't know how to find standard deviation I'm sorry ._.

Answer 2

First you need to find the mean? Do you know how?

Answer 3

Yup! The mean is 119.

Answer 4

Oh wait I forgot a step hold on

Answer 5

17

Answer 6

\[mean = \frac{ 21 + 6 + 18 + 21 + 20 + 14 + 19 }{ 7 }\]

Answer 7

And that's 17, right?

Answer 8

Indeed :)
The mean is 17

Answer 9

So now, Find the Variance...
Do you know how to find the variance?

Answer 10

I do not ):

Answer 11

\[\sigma^2 = \frac{ (21 - 17)^2 + (6 - 17)^2 + (18 - 17)^2 + (21 - 17)^2 + (20 - 17)^2 + (14 - 17)^2 + (19 - 17)^2 }{ 7 }\]

Answer 12

so it is basically:
(# - mean)^2 + (# - mean)^2 ..... / the total number of #s

Answer 13

Are you with me @TammisaurusRex ?

Answer 14

Oh! Okay! Calculating it now (:

Answer 15

Okaii :)

Answer 16

It would be 25.14 (rounded), right?

Answer 17

\[\frac{ 176 }{ 7 } \approx 25.14\]

Answer 18

So yes, indeed :)
Good Job :)

So now to find the standard deviation :)

Answer 19

Oh, I didn't know there was further solving.. my answer options have that double ~ symbol and numbers, I don't think they wanted me to solve it all the way

Answer 20

Find the Standard Deviation:

\[\sigma = \sqrt{variance}\]

\[\sigma = \sqrt{\frac{ 176 }{ 7 }}\]

\[\sigma = \sqrt{25.14}\]
\[\sigma \approx 5.01\]

Answer 21

\[\approx \]

this is just approximately

Answer 22

Oh! I see (: Thank you!

Answer 23

yw :)

No problem :D